1. Field of the Invention
The present invention relates to a gas discharge panel such as a plasma display panel (PDP) and its production method. The gas discharge panel according to the present invention is suitably used for household TVs, computer monitors, as well as large-screen displays for displaying information provided at stations, airports, stock exchanges, factories, schools and the like.
2. Description of Related Art
Conventionally, a plasma display panel (PDP), a plasma addressing liquid crystal (PALC) and the like are known as a gas discharge panel. Among these gas discharge panels, the PDP is characterized by large size and small thickness, and is one of the largest selling display devices at the present time.
FIG. 1 illustrates a schematic perspective view of a representative PDP which is in practical use.
The PDP of FIG. 1 is constituted of a front side substrate and a rear side substrate.
The front side substrate 10 is generally comprised of a plurality of display electrodes (sustain electrodes X, Y to be paired) formed on a glass substrate 11, a dielectric layer 17 formed so as to cover the display electrodes X, Y, and a protective film 18 formed on the dielectric layer 17 and exposed to a discharge space.
The display electrodes X, Y are each comprised of a transparent electrode film 41, and a bus electrode 42 laminated on an edge of the transparent electrode film 41 for reducing the resistance of the film 41. The bus electrode 42 is narrower in width than the transparent electrode film.
The rear side substrate 20 is generally comprised of a plurality of address electrodes A formed on a glass substrate 21, a dielectric layer 24 covering the address electrodes A, a plurality of band-shaped barrier ribs 29 formed on the dielectric layer 24 and between adjacent address electrodes, and phosphor layers 28R, 28G and 28B each formed between the barrier ribs to extend onto the walls of the barrier ribs.
The aforesaid front side and rear side substrates are arranged with the display electrodes and address electrodes, which are placed to be adjacent to each other, opposed so that both the electrodes intersect at right angles, and the periphery of the substrates is sealed with a sealing glass layer and a space surrounded by the barrier ribs 29 is filled with a discharge gas (for example, Ne—Xe gas), thereby to form a PDP 1. In FIG. 1, R, G and B respectively represent unit light-emitting areas of red, green and blue, and one pixel is constituted of RGB arranged in a lateral direction.
In the aforesaid construction of the PDP, when an electric field is applied between the display electrodes and address electrodes, a discharge gas is excited and ionized therebetween to discharge vacuum ultraviolet rays. At this time, the discharged vacuum UV rays are in contact with a phosphor, so that visible light is discharged by the phosphor for utilizing it for display.
The dielectric layer is generally formed by using of a glass paste obtained by dispensing low-melting glass into a vehicle containing ethyl cellulose resin as a main component or a glass sheet obtained by dispensing the low-melting glass into an acrylic resin or the like. The glass paste or glass sheet is baked to burn out the resin components for melting the low-melting glass contained therein, thereby forming the dielectric layer.
Japanese Unexamined Patent Publication No.2000-21304 has reported recently a PDP comprising a dielectric layer formed by a vapor phase growth method such as a CVD-method or the like instead of the dielectric layer composed of the low-melting glass, in order to improve the panel performance of a PDP.
Japanese Unexamined Patent Publication No.2001-155647 proposes a cover film provided on a dielectric film in order to suppress the deterioration of a phosphor by a NH3 base gas generated by the dielectric film formed by the CVD method.
In order to enhance the producing speed of the PDP, it is desired to increase the forming speed of the dielectric layer. However, even if only the layer forming speed is raised, an impurity gas is increased in the dielectric layer. Accordingly, the impurity gas is discharged, resulting in deterioration of the phosphor. The cover film is also insufficient for suppressing the discharge of impurity gas. When the layer forming speed is further increased, a number of defects such as a crack in the dielectric layer, the nonuniform thickness of the dielectric layer and the like will occur. These defects allow the dielectric layer to be partially deteriorated, so that a panel lifetime is shortened.